Migraine or Headache? Headaches, one of the most common nervous-system disorders, range from uncomfortable annoyances to debilitating. Because of their dubious symptoms, headache disorders are under-reported and under-treated. Four types of headache disorders are recognized by the World Health Organization (WHO): migraines, tension headaches, medication-overuse headaches, and cluster-headaches. Migraines are the most severe of these